1. Field of the Invention
The invention relates to a method and a device for active radial control of wheel pairs or wheel sets on vehicles. The invention is particularly suitable for, but not limited to, use in rail vehicles.
2. Description of the Related Art
A number of mechanical devices for the quasi-static setting of wheel pairs or wheel sets, hereinafter collectively referred to as wheel units, in track curves are known, which devices comprise passive or active means. In an active control system, the wheel units are aligned and fixed according to the radius of curvature. Such devices steer the wheel unit at a fixed relationship to the radius of curvature, thus achieving equalisation of the sums of the transverse forces acting upon the wheel units of a running gear or a vehicle at the most for a limited range. These arrangements are associated with a disadvantage in that the running stability is no better than it is in conventional running gear with rigid longitudinal guidance of the wheel units; at best the results are no worse. Furthermore, mechanical devices, for example roll stabilisers or friction-torque inhibitors are used to ensure running stability. Such mechanical devices can only be a compromise between the ability to handle curves and running stability, and, generally speaking, result in an excitation of structural oscillation in the carriage body. Frequently, additional damping elements in the wheel unit coupling are necessary.
EP 0 785 123 B1 describes a method for obtaining and processing data for the tracking of running gear comprising individual wheel units. In a method disclosed therein, the turning movement of the running gear is scanned with zero force as an angle, angular speed or angular acceleration, by means of angle sensors; the measured value or values is/are disaggregated into their frequency fractions; movements which protrude from the frequency spectra are detected as disturbing, according to amplitude, frequency and phase position; after rotation by 180° and processing, the vector or vectors identified in this way is/are supplied to a control or regulating system as information for changing the setting angle of the running gear; and the control or regulating system eliminates the disturbing motion components from the running gear movement. The invention does not take into account transverse forces between the wheel pair or wheel set and the track.
From EP 0 374 290 B1, a rail vehicle is known which on both sides along the longitudinal axis of the vehicle comprises a specifiable number of individual wheels which can be swivelled by steering action. Steering, free of any tracking error, of each individual wheel in curved sections is made possible by the provision of a device which measures the course of the track, with said device measuring the deviation of a vehicle axis from the course of the track, wherein said device, depending on the measured deviation, generates a steering signal for each individual wheel independently of the respective other wheel. Proposed devices which measure the course of the track include non-contacting systems which function on an opto-electronic or magnetic or electromagnetic basis. The invention cannot be used in conjunction with vehicles comprising wheel pairs or wheel sets.
The Japanese group of applications JP A 06199236, JP A 07081564 and JP A 07081565 describes influencing the wave running or sinusoidal running by means of hydraulic actuators between the bogie frame and the wheel set bearings. It is based on identifying the frequency of the wave running in a spectrum of the sensed translatory vibrations or yaw vibrations, wherein at least eight sensors for each bogie, as well as an extended data collection with a subsequent frequency analysis, are required.
All the hitherto known methods and devices for influencing the running characteristics of wheel units are associated with the disadvantage that they only serve the following:
1. in curves, i.e. during travelling in track curves, to bring about the corresponding tracking by steering, and/or
2. to determine the frequency of the wave running and to influence it with the same frequency, a process which requires Fourier transformation which means lost time in relation to quickly-changing profile parameters in the wheel-rail contact,
but that they do not have a stabilising action on the wheel sets or wheel pairs in the sense of a real-time reaction on the current load situation and motion situation, which situations can change quickly. On a straight section of track, these measures at best make a very limited contribution to improved tracking.